<div class="shop_ctn">

  <?php $response = $this->nexmo->get_balance(); ?>
        <h3>Account Balance: <?=$response->value?> €</h3>
       <input type="button" value="charge" onclick="window.open('https://dashboard.nexmo.com/login','_black')">
    <h4>Response Code: <?=$this->nexmo->get_http_status()?></h4>
</div>

</body>
</html>